Corona discharge is widely used to treat the surfaces of plastic parts such as organic glass optical lenses in order to improve the adhesion properties of the surfaces. In most cases, such parts are just placed on a belt or a similar device and the surface to be treated does not touch any other material. If the lens is submitted to several treatment steps then manual handling is generally required to put on and to take the lens off the belt.
However, manual handling is troublesome.
The object of the invention is to provide a new means for handling the lens during a corona treatment without inducing any damage to the lens during the corona treatment and during the handling.
According to the invention, one uses a means holding the part by its periphery so that the treated surface of the part be held in front of the active area of the treating device, for example the electric arc in a corona discharge treatment. In such circumstances, an area of overheating might occur at the contact points between the part and the holder and burns or defects due to heat might be observed.
An object of the invention is to provide an optical lens holder which reduces, preferably avoids, the apparition of burned or overheated areas around the contact points of the optical lens with the holder. Thus, to reduce or avoid the appearance of such defects, in particular during a corona discharge treatment of the optical lens, it has been determined according to the invention that accumulation of electric charges on the treated lens shall be avoided as such an accumulation can create an area of overheating especially at the contact points between the optical lens and the holder. Also, it is important that heat created in the lens during the treatment, in particular at the contact points, be dissipated as fast as possible. Of course, the means used to obtain the diminution or disappearance of the defects shall not detrimentally interfere with the treating process and in particular with a corona discharge treatment.